Can't Find Typed Word, But Finds Pasted Word

All of a sudden, I'm having trouble searching for words in the editor in one particular book. If I type in a word to search for (any word), it won't find it. If I copy a word and paste it in the search bar, it finds it. I keep staring at the screen trying to see what I'm doing wrong (including spelling), but don't see anything.

Here's a screenshot of my latest attempt (the cursor is one line above that word I'm searching for). It finds nothing. Here's the error message:
Those asterisks and the pre-style stuff don't show up in the actual error message. I assume they're just for display purposed in the Editor. Maybe the asterisks are soft-hyphens for some reason?

EDIT: I've gone so far as to reboot the computer and try again. Still doesn't work. I can search fine in other books.

EDIT2: This is even weirder than I thought. I proceeded to search for other things, and the searches worked. I tried the search I showed here ("important") and it didn't find any instances of that word. Copy/Pasting it again lets it find all instances. If I search for other words in that sentence, it finds some, but not others. For instance (going down the sentence) "Shut up", "he", "told", "them" all work. But, the next word in the sentence ("quietly") does not.

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